Delivery catheter including side port and electrodes

ABSTRACT

A delivery catheter, including a catheter body, a side port, a first electrode, and a second electrode, is described. The catheter body may comprise a proximal end, a distal end, and a perimeter surface. The catheter body defines a delivery lumen extending longitudinally within the catheter body. The side port is defined in the perimeter surface of the catheter body proximate the distal end and in communication with the delivery lumen. The electrodes may be adjacent to and spaced from the side port. Techniques for using the delivery catheter to identify a desired lead implantation location, e.g., via the electrodes, and implant a medical lead or other implantable element at the desired location through the delivery lumen and side port are also described.

TECHNICAL FIELD

The disclosure generally relates to a delivery catheter for deliveringan implantable medical lead or other implantable element to anelectrical stimulation site.

BACKGROUND

Specialized groups of cardiac cells that form the cardiac conductionsystem control the frequency, pathway of conduction, and rate ofpropagation of action potentials through the heart, which cause theheart to beat in an efficient manner. This special conduction systemincludes the sinoatrial node (SA node), the atrial internodal tracts,the atrioventricular node (AV node), the His bundle, and the right andleft bundle branches.

The SA node, located at the junction of the superior vena cava and rightatrium, normally acts as the natural pacemaker, generating actionpotentials, which are conducted through the rest of the heart. Whennormal conduction pathways are intact, an action potential generated inthe SA node is conducted through the atria and to the AV node via theatrial internodal tracts. The conduction through the AV nodal tissuetakes longer than through the atrial tissue, resulting in a delaybetween atrial contraction and the start of ventricular contraction.

The AV node, located in the central fibrous body, conducts the actionpotential to the His bundle, located under the annulus of the tricuspidvalve. The His bundle splits into the left and right bundle branches,which conduct the action potential to specialized fibers called“Purkinje fibers.” The bundle branches rapidly conduct the actionpotential down the ventricular septum, where the Purkinje fibers spreadthe depolarization wavefront quickly to the remaining ventricularmyocardium, producing a coordinated contraction of the ventricularmuscle mass.

Conduction abnormalities may cause slowed or disrupted conductionanywhere along this conduction pathway. For example, the SA node may notgenerate action potentials at a fast enough rate resulting in too slowof heart rate, or bradycardia. AV block may prevent conduction of theaction potential from the atria to the ventricles. A left and rightbundle branch block, or other conduction abnormalities in the Purkinjefibers or ventricular myocardium, may cause the contraction of the rightand left ventricles to be asynchronous. These and other conductionabnormalities may be treated by an external or implantable pacemaker.

Pacemakers are typically coupled to the heart via one or moreimplantable leads, each carrying one or more electrodes for stimulatingthe heart and for sensing the intrinsic electrical signals associatedwith a conducted action potential. Electrodes are commonly placed on theendocardial surface using a transvenous approach. For example, a rightventricular lead may be advanced into the right ventricle and placedsuch that an electrode is positioned at or near the right ventricularapex. Low capture thresholds and stable lead positioning have made theright ventricular apex a preferred ventricular stimulation site.

However, ventricular pacing at the location of the right ventricularapex does not mimic the normal ventricular conduction pathway. Bothexperimental and clinical studies have shown that septal pacing canimprove various indices of cardiac function compared to apical pacing.Direct myocardial stimulation, as occurs in apical pacing, can causeremodeling of the ventricular myocardium, including myofibrilar disarrayand local hypertrophy away from the electrode.

The most normal physiological approach to pacing the ventricles whennormal AV nodal conduction fails may be to deliver electricalstimulation pulses directly to the His bundle. Depolarization of the Hisbundle tissue may be conducted normally through the ventricularconduction pathway, down the left and right bundle branches and to theremainder of the ventricular myocardium. The resulting ventricularcontraction, which is more rapid and results in a narrow QRS complex anda more vigorous, normal contraction, may produce a better-coordinatedventricle contraction for achieving efficient heart pumping action.

In some cases, left ventricular (LV) pacing/sensing may be desiredinstead of, or in addition to right ventricular (RV) pacing/sensing. Forexample, RV and LV pacing may be provided in a time coordinated fashionto resynchronize the contraction of the ventricles, e.g., providecardiac resynchronization therapy (CRT), which may be indicated forcardimyopathy or other ventricular conduction abnormalities. For LVpacing/sensing, a lead may be transvenously advanced through the rightventricle, into the coronary sinus and, in some cases, a coronary veinbranching from the coronary sinus, to place electrodes near themyocardium of the left ventricle.

Leads may also be transvenously implanted in one or both atria.Furthermore, in some cases, cardiac pacing/sensing leads cannot be, orfor some other reason are not implanted transvenously. In such cases, alead may be epicardially implanted by fixing an electrode at the distaltip of the lead to the myocardium through an incision or puncture in thepericardium.

SUMMARY

In general, the disclosure is directed to a delivery catheter configuredto facilitate identification of a desired location for implantation of amedical lead, and implantation of the lead at the desired location, aswell as methods for using the delivery catheter to identify the desiredlocation and implant a medical lead at the desired location. As oneexample, a delivery catheter may facilitate delivering a stimulationlead to a desired location proximate the His bundle for His bundlepacing. The delivery catheter may include a plurality of electrodes, adelivery lumen, and a side port. The electrodes may be electricallycoupled to sensing circuitry, e.g., for sensing an electrocardiogram(ECG). The electrodes may be used to determine a desired implantationlocation, such as, for example, a desired stimulation location. Once thedesired location is determined, a lead may be advanced through thedelivery lumen and out the side port to the desired location.

In one embodiment, the disclosure is directed to a delivery catheter.The delivery catheter may include a catheter body, a side port, a firstelectrode, and a second electrode. The catheter body may comprise aproximal end, a distal end, and a perimeter surface. Further, thecatheter body defines a delivery lumen extending longitudinally withinthe catheter body. The side port is defined in the perimeter surface ofthe catheter body proximate the distal end and in communication with thedelivery lumen. Each of the first and second electrodes is adjacent toand spaced from the side port.

In another embodiment, the disclosure is directed to kit including adelivery catheter and an implantable element for at least one of therapydelivery or sensing. The delivery catheter may include a catheter body,a side port, a first electrode, and a second electrode. The catheterbody may comprise a proximal end, a distal end, and a perimeter surface.Further, the catheter body defines a delivery lumen extendinglongitudinally within the catheter body. The side port is defined in theperimeter surface of the catheter body proximate the distal end and incommunication with the delivery lumen. Each of the first and secondelectrodes is adjacent to and spaced from the side port.

In yet another embodiment, the disclosure is directed to a method thatcomprises advancing a delivery catheter toward a desired location withina patient. The delivery catheter comprises a catheter body including aproximal end, a distal end and a perimeter surface. The catheter bodydefines a delivery lumen extending longitudinally within the catheterbody. The delivery catheter also includes a side port defined in theperimeter surface of the catheter body proximate the distal end and incommunication with the delivery lumen. The delivery catheter furtherincludes a first electrode and a second electrode. Each of the first andsecond electrodes is adjacent to and spaced from the side port. Themethod also includes identifying the desired location with the firstelectrode and the second electrode, advancing an implantable element forat least one of therapy delivery or sensing through the delivery lumenand out the side port to the desired location, and withdrawing thedelivery catheter from patient.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating a right side of a heart andincludes an example delivery catheter inserted through the superior venacava and right atrium into the right ventricle.

FIG. 2A is a side view illustrating the example delivery catheter ofFIG. 1 and a lead exiting the catheter and attached to a surface.

FIG. 2B is a cross-sectional view of the delivery catheter of FIG. 2Ataken along line 2B.

FIG. 3 is a side view illustrating another example delivery catheter.

FIG. 4 is a cross-sectional side view illustrating another exampledelivery catheter including a guide wire lumen.

FIG. 5 is a cross-sectional side view illustrating another exampledelivery catheter including a movable deflection member and a guide wiredisposed in the catheter.

FIG. 6 is a cross-sectional side view illustrating the delivery catheterincluding the movable deflection member of FIG. 5 and a lead advancedthrough the catheter.

FIG. 7 is a schematic side view illustrating an example deliverycatheter in a patient lumen and a lead exiting a side port and enteringa second patient lumen.

FIG. 8 is a flow diagram illustrating an example method of delivering amedical lead to a desired location using a delivery catheter.

FIG. 9 is a flow diagram illustrating an example method of delivering amedical lead to a desired location using a delivery catheter and a guidewire.

DETAILED DESCRIPTION

In general, the present disclosure is directed to a delivery catheterand methods of using the delivery catheter. The delivery catheter may beused to deliver a sensing lead, stimulation lead or drug deliverycatheter to a desired location within a patient. In general, the patientmay be a human patient. However, in other embodiments, the patient maybe a non-human patient. The desired location may generally include anysite within the patient where stimulation, sensing, or drug delivery isdesired. In some embodiments, the desired location includes a Hisbundle, a coronary vein, or tissue suitable for pacing, which is notdead, damaged, or otherwise not operating within general anatomicalnorms.

The delivery catheter may include features that facilitate determinationof the desired location. For example, the delivery catheter may includeat least two electrodes for sensing a waveform, such as an ECG. Thedesired location may be determined based on a characteristic of thewaveform, such as the amplitude or the presence of certain waveformfeatures.

The delivery catheter may also include features that facilitate deliveryof the lead or drug delivery catheter at an angle to the longitudinalaxis of the delivery catheter. For example, the delivery catheter mayinclude a side port defined in a perimeter surface of the catheter,through which the lead or drug delivery catheter exits a lumen of thedelivery catheter. In some embodiments, the delivery catheter mayinclude a deflection member which deflects the lead or drug deliverycatheter out of the side port.

In this disclosure, the delivery catheter will be primarily describedwith reference to delivering a stimulation lead to a location proximatea His bundle in a heart. However, it will be understood that deliverycatheters of the present disclosure are not limited to deliveringstimulation leads to a His bundle. For example, delivery cathetersdescribed herein may be used to deliver leads to a coronary vein, toepicardial tissue, or other locations. Additionally, delivery cathetersdescribed herein may be used to deliver leads for neurostimulationtherapy (e.g., spinal cord stimulation), deep brain stimulation,stimulation of one or more muscles, muscle groups or organs, and,generally, stimulation of tissue of a patient. Further, in someembodiments the delivery catheters described herein can be used todeliver catheters for dispensing a drug or other beneficial agent froman implanted or external drug delivery device. In short, the deliverycatheters described herein can find useful application in delivery of awide variety of leads or catheters for delivery of therapy to a patientor patient sensing.

FIG. 1 is a schematic diagram of a right side of a heart 14 having ananterior-lateral wall peeled back to present a portion of the heart'sintrinsic conduction system and chambers of a right atrium (RA) 10 and aright ventricle (RV) 6. Pertinent elements of the heart's intrinsicconduction system, illustrated in FIG. 1, include a sinoatrial (SA) node1, an atrioventricular (AV) node 2, a His bundle 3, a right bundlebranch 4, and Purkinje fibers 5. SA node 1 is shown near the superiorvena cava (SVC) 12 in the RA 10. An electrical impulse starting at theSA node 1 travels rapidly through tissue of RA 10 and tissue of a leftatrium (not shown) to AV node 2. At AV node 2, the impulse slows tocreate a delay before passing on through His bundle 3, which branches,in an interventricular septum 7, into a right bundle branch 4 and a leftbundle branch (not shown) and then, near RV apex 16, into Purkinjefibers 5. Flow of the electrical impulse creates an orderly sequence ofatrial and ventricular contraction and relaxation to efficiently pumpblood through heart 14.

Due to disease, injury, or natural defects, the intrinsic conductionsystem of heart 14 may no longer operate within general anatomicalnorms. Consequently, a cardiac pacemaker system can be implanted into apatient such that electrodes carried by an implantable medical lead areplaced in an atrial appendage 15. The electrodes stimulate RA 10downstream of SA node 1 and the stimulating pulse travels on to AV node2, His bundle 3, and Purkinje fibers 5 to restore physiologicalcontraction of the heart. However, if a patient has a defective AV node2, pacing in atrial appendage 15 will not be effective, since the pacingsite is upstream of AV node 2. Such a patient may have a cardiacpacemaker system implanted such that lead electrodes are placed in an RVapex 16. RV apex 16 has been an accepted site for pacing since it is arelatively easy to engage lead electrodes at this site, and pacing fromthis site has been demonstrated safe and effective. Due to questionsraised by recent studies looking into long-term effects of pacing fromRV apex 16, as previously described, there is a great deal of interestin more physiologically correct pacing.

One site for more physiologically correct pacing is the His bundle 3. Asdescribed above, the His bundle 3 forms part of the intrinsic conductionsystem of heart 14, and any pacing applied from the His bundle 3 willconduct through the His bundle 3 to the Purkinje fibers 5 and throughoutthe right ventricle 6 and left ventricle (not shown). However,determining the location of the His bundle 3 and attaching a leadproximate to the His bundle 3 may be difficult.

For example, one preferred location from which the His bundle 3 may bepaced is proximate to and under the tricuspid valve. This location maybe accessed from the right ventricle, and may be difficult to reachusing a distal port delivery catheter. Further, once this location isreached, it may be challenging to maintain a distal port deliverycatheter in position as the lead is fixed to the His bundle 3 or tissueproximate the His bundle 3. Additionally, locating the His bundle 3 maybe difficult in at least some hearts, because the His bundle 3 may notbe reliably locatable in some patients using imaging techniques.

FIG. 1 illustrates a portion of an example delivery catheter 8, whichincludes features that may facilitate locating His bundle 3, deliveringa lead to His bundle 3 or tissue adjacent His bundle 3, and fixing thelead to His bundle 3 or the adjacent tissue. For example, the deliverycatheter 8 includes a side port 9 located proximate to a distal end 11of the catheter 8 and in communication with an internal lumen 22 ofdelivery catheter 8 (FIG. 2B). Delivery catheter 8 also includeselectrodes 27 located adjacent to and spaced from side port 9. Theproximal end of delivery catheter 8 is not shown in FIG. 1.

Delivery catheter 8 may be inserted into the heart using a transvenousapproach through the SVC 12 into the right atrium 10 and may be directedthrough the tricuspid valve 13 to RV 6. In some embodiments, deliverycatheter 8 is a steerable catheter. That is, in some embodiments, thedelivery catheter 8 includes features that allow it to effectivelytransfer force applied to a proximal end, e.g., handle, of the deliverycatheter 8 into motion of a distal end of delivery catheter 8. In otherembodiments, delivery catheter 8 is a guidable catheter and includes alumen for receiving a guide wire to assist with advancing the catheter 8into a desired position within the heart.

Delivery catheter 8 may comprise a flexible, biocompatible material suchas, for example, silicone or polyurethane. In some embodiments, deliverycatheter 8 may further include a radiopaque marker to facilitatefluoroscopic or other visualization of the catheter, e.g., for steeringand/or orienting the catheter, as it is being delivered to the targettissue site. A length of delivery catheter 8 may vary, but may bebetween about 30 and 60 centimeters, with an outer diameter of less thanabout 10 French, or about 0.131 inches.

As illustrated in FIG. 1, a curve, multiple curves, or any other shapemay be formed in a distal portion 18 of the catheter 8 proximate distalend 11 and to assist in bringing distal end 11 into contact with Hisbundle 3 or tissue proximate His bundle 3. In some embodiments, thecurve(s) or other shape may be formed in catheter 8 through use of aguide wire (not shown) that includes the desired curve or shape, or anactuation member at a proximal end of the delivery catheter 8 that canbe manipulated to induce the desired curve(s) or shape in distal portion18. For example, in some embodiments the actuation member (not shown)may be a rotatable thumb wheel coupled to one or more pull wiresattached to an off-axis attachment point near distal end 11. Byactuating the rotatable thumb wheel, the pull wire(s) may be tightened,which may cause distal end 11 to deflect and induce the desired shape indistal portion 18.

In other embodiments, such as, for example, when the delivery catheter 8is a steerable catheter, the catheter 8 may include a pre-formed curveor shape. Delivery catheter 8 may be flexible to facilitate advancementof the catheter 8 through the circulatory system (including SVC 12).Upon advancing into RA 10, catheter 8 may begin to regain its pre-formedcurve or shape. The catheter 8 may then be advanced through thetricuspid valve 13 and into the right ventricle 6, where distal end 11of catheter 8 is directed into contact with endocardial tissue proximateto His bundle 3.

Side port 9 is located on a perimeter surface 17 (FIG. 2A) of deliverycatheter 8 proximate to distal end 11. In some embodiments, side port 9may be located on a portion of the perimeter surface 17 that is inwardlyoriented when the pre-formed curve of the distal portion 18 of catheter8 is present. In other embodiments, delivery catheter 8 may bemanipulated (e.g., rotated or twisted) to inwardly or outwardly orientside port 9.

Because side port 9 forms the exit through which lead 23 is advanced, insome embodiments the distal end 11 of lead may be a blind end. That is,distal end 11 may not include an orifice in communication with theinternal lumen 22 of catheter 8. In other embodiments, internal lumen 22may extend fully from proximal end of delivery catheter 8 to distal end11 of catheter 8.

FIG. 2A is a side view illustrating distal portion 18 of deliverycatheter 8 and a lead 23 exiting the catheter and attached to a surface.FIG. 2B is a cross-sectional view of the delivery catheter 8 taken alongline 2B, which is illustrated in FIG. 2A. As shown in FIG. 2A, the sideport 9 may be manipulated to be proximate to surface 21 of tissue 29,which may be tissue of His bundle 3, or endocardial tissue near Hisbundle 3. Side port 9 provides an exit orifice through which lead 23 mayexit delivery catheter 8 to be fixed to tissue 29 by fixation element25. The side port 9 may be in communication with an internal lumen 22(see FIG. 2B) defined within delivery catheter 8. Lead 23 may beadvanced through the internal lumen 22 from a proximal end (not shown)of delivery catheter 8 to the distal end 11 of catheter 8 and exitthrough side port 9.

In the embodiment illustrated in FIG. 2A and FIG. 2B, the fixationelement 25 is a helical fixation element, which, in some embodiments,may also function as a sensing or stimulation electrode. In otherembodiments, however, another type of fixation element 25 may be used,and fixation element 25 and the electrode may be separate structures.For example, fixation element 25 may comprise a hook, a barb, anexpandable fixation element, an adhesive, a tissue ingrowth element suchas a mesh fiber, or a combination of more than one element. In theembodiment illustrated in FIGS. 2A and 2B, once the lead 23 exitsthrough side port 9 and contacts surface 21, the lead body is rotated toadvance the fixation element 25 through surface 21 and into the tissue29. In other embodiments, lead 23 may be manipulated appropriately tocause fixation element 25 to attach lead 23 to tissue 29.

Delivery catheter 8 also includes a first electrode 27 a and a secondelectrode 27 b (collectively “electrodes 27”). Electrodes 27 are eachlocated adjacent to and spaced from side port 9. In the embodiment shownin FIGS. 2A and 2B, first electrode 27 a is distal from side port 9 andsecond electrode 27 b is proximal from side port 9. In otherembodiments, as described below, both electrodes 27 may be proximal ordistal from side port 9. In some embodiments, each of electrodes 27 isspaced at least about 2 millimeters from an adjacent edge of side port9.

In some embodiments, delivery catheter 8 may include conductors (notshown) that electrically couple electrodes 27 to an external device (notshown), e.g., via a connector (not shown) comprising electrical contactson a proximal portion of catheter 8. The external device may includecircuitry for receiving and conditioning physiological signals of apatient via electrodes 27. In some embodiments, the external device mayinclude a user interface, which may comprise a display for displayingthe physiological signals. In some embodiments, the external device mayinclude circuitry, such as digital signal processor (DSP),microprocessor, application specific integrated circuit (ASIC), or otherprocessor or processing circuitry, for processing the signal, e.g., forautomatically detecting features in the signal.

In some embodiments, the physiological signal is an electrocardiogram(ECG). The external device or a user, e.g., physician, may detect thelocation of His bundle 3 based on the ECG waveform. For example, whenthe electrodes 27 are located adjacent His bundle 3, the ECG waveformmay include the atrial P-wave, ventricular QRS signature, and a Hisspike between the P-wave and QRS signature. Thus, translating thecatheter 8 along surface 21 while collecting an ECG may allowdetermination of a location of His bundle 3.

As an example of an embodiment in which the external device comprises aprocessor capable of detecting features within a physiological signal,the processor may be capable of detecting an electrical potentialwaveform indicative of the His bundle 3. For example, the His bundle 3has a signature waveform with a frequency of about 200 Hz, which may bedetectable by the processor.

Further, in some embodiments, the ECG may be used to differentiatebetween viable tissue suitable for pacing and dead (ischemic) or damagedtissue unsuitable for pacing. For example, the ECG may include a lowervoltage amplitude when electrodes 27 are adjacent dead or damaged tissuecompared to when electrodes 27 are adjacent viable tissue.

In some embodiments, the conductors may electrically couple theelectrodes 27 to an electrical energy source, which may be part of thesame external device used for signal monitoring, or a different externaldevice. The electrical energy source may apply a voltage or currentbetween the first electrode 27 a and second electrode 27 b. Whenelectrodes 27 are in contact with surface 21 of tissue 29, theelectrical energy travels through the tissue 29 and an impedance of thetissue 29 may be determined by measuring the electrical current orvoltage, and calculating impedance based on the measured value and theapplied voltage or current. By scanning the lead across the tissue andmonitoring the impedance, the location of the His bundle 3 may bedetermined. Specifically, tissue comprising the His bundle 3 may exhibita lower impedance than an impedance of adjacent endocardial tissue. Infact, an impedance of tissue of the His bundle 3 may be about 50% lowerthan an impedance of adjacent endocardial tissue.

In some embodiments, delivery catheter 8 also includes a feature 24which may facilitate withdrawal of the delivery catheter 8 once lead 23is in the desired position. For example, the feature 24 may comprise athin silver strip which allows a physician to cut delivery catheter 8more easily. In other embodiments, the feature 24 may comprise a thingroove or perforation that enables a physician to tear catheter, or asubstantially longitudinally-oriented tear strip that a physician mayuse to tear catheter 8. In some embodiments, delivery catheter does notinclude such a feature 24.

FIG. 3 illustrates another example delivery catheter 30, which includesa single delivery lumen 32. The delivery lumen 32 is defined by thecatheter body 34 and extends substantially longitudinally withincatheter body 34 from catheter proximal end 36 to catheter distal end38. The delivery catheter 30 further includes a side port 40 defined inperimeter surface 42, a first electrode 44 a and a second electrode 44 b(collectively “electrodes 44”).

Delivery lumen 32 is in communication with side port 40. In theembodiment illustrated in FIG. 3, the delivery catheter 30 includes adeflection member 46, which is shaped to deflect a lead (e.g., lead 25)advancing substantially longitudinally through lumen 32 to extend outthrough side port 40. For example, the deflection member 46 may includea curved surface (FIG. 3), a sloped surface (FIG. 4), a movable flap(FIGS. 5 and 6), or the like. In some embodiments, delivery catheter 30may not include a deflection member 46, and lumen 32 may terminate in asubstantially flat wall proximate distal periphery 40 a of side port 40.

In some embodiments, deflection member 46 may be shaped such that thelead exits side port 40 about orthogonal to the longitudinal axis 48 ofthe catheter 30. In other embodiments, deflection member 46 may beshaped such that the lead exits side port 40 at a non-orthogonal angleto longitudinal axis 48 of catheter 30.

FIG. 3 also illustrates electrodes 44 both located adjacent to andseparated from side port 40. In FIG. 3, each of electrodes 44 is locateddistal from port 40, and is electrically coupled to a respective one ofconductors 50, which extend to proximal end 36 of delivery catheter 36.While not shown in FIG. 3, conductors 50 may include, at their proximalends, connectors for electrically connecting to an external device, suchas a monitor, display, ECG machine, voltage source or waveform detector,as described above.

FIG. 4 illustrates a cross-sectional view of another example embodimentof a delivery catheter 60. Certain aspects of catheter 60 are similar tocatheter 8 and catheter 30 of FIGS. 1, 2 and 3. For example, deliverycatheter 60 includes a catheter body 64, which defines a delivery lumen62 extending substantially longitudinally within catheter body 64 from acatheter proximal end 66 substantially to a catheter distal end 68.Delivery catheter 60 further includes a side port 70, defined inperimeter surface 72, in communication with delivery lumen 62. Catheterbody 64 also includes a deflection member 76, which in the embodimentillustrated in FIG. 4, is a sloped surface connecting distal periphery70 a of side port 70 with a catheter lumen wall 62 a. Deflection member76 may deflect a lead advanced through delivery lumen 62 out throughside port 70.

Delivery catheter 60 further includes a guide wire lumen 80 defined bycatheter body 64 and extending substantially longitudinally fromcatheter proximal end 66 to catheter distal end 68. Guide wire lumen 80may receive a guide wire for guiding the delivery catheter 60 into adesired position, such as into a desired position in a right ventricleof a heart.

FIGS. 5 and 6 illustrate an example delivery catheter 90 including asingle delivery lumen 92 defined in catheter body 94. Delivery lumen 92extends fully from catheter proximal end 104 to catheter distal end 98.The delivery catheter 90 further includes a deflection member comprisinga movable flap 100. Movable flap 100 may be used to provide a singlelumen delivery catheter 90 that is capable of receiving a guide wire102.

In the embodiment illustrated in FIGS. 5 and 6, the guide wire 102 mayfirst be advanced to proximate the desired location for introduction ofa lead 104 or drug delivery catheter. Once the guide wire 102 isproximate the desired location, the delivery catheter 90 may be advancedover guide wire 102, with guide wire 102 disposed in delivery lumen 92.As the distal end 98 of catheter 90 is advanced over guide wire 102, themovable flap 100 deforms and moves to an up or open position, as shownin FIG. 5. Delivery catheter 90 may be advanced over guide wire 102until side port 96 is proximate the desired location. In someembodiments, catheter 90 includes at least two electrodes fordetermining the desired location, as described above. Once the deliverycatheter 90 (e.g., side port 96) is located in the desired position, theguide wire 102 may be withdrawn through distal end 104 of the catheter90.

When guide wire 102 is withdrawn from delivery lumen 92, the movableflap 100 is no longer being deformed, and returns to a down or closedposition, as shown in FIG. 6. In the closed configuration, the movableflap 100 forms a deflection surface which can deflect a lead 104advanced through delivery lumen 92 out side port 96, as shown in FIG. 6.

A delivery catheter 90 including a single delivery lumen 92 and amovable flap 100 may provide a delivery catheter with a smaller outerdiameter compared to a delivery catheter with both a delivery lumen anda guide wire lumen, such as catheter 60 of FIG. 4, while stillpermitting the use of a guide wire 102 during advancement of thecatheter to a desired location within a patient. In embodiments wherethe lead 104 is to be delivered to a small diameter lumen, such as asmall artery or vein, it may be desirable to form the delivery catheter90 with as small an outer diameter as possible.

While the disclosure hereinabove has been generally directed to deliverycatheters for transvenous introduction of a stimulation lead to alocation proximate the His bundle, delivery catheters according to thisdisclosure may find applicability in other situations. For example, asillustrated in FIG. 7, a delivery catheter 110 may be used to deliver alead 112 to a location through the coronary sinus. In many cases, it isdesired that the lead 112 be advanced through coronary sinus 114 andinto a coronary vein 116. Some of the most desirable coronary veins 116branch off coronary sinus 114 substantially perpendicularly. It may bedifficult to direct the lead 112 or a conventional catheter from thecoronary sinus 114 to the coronary vein 116 when the angle issubstantially perpendicular. However, delivery catheter 110, whichincludes side port 118, facilitates the advancement of the lead 112 intocoronary vein 116, as shown in FIG. 7.

Additionally, delivery catheter 110 includes a first electrode 120 adistal from side port 118 and a second electrode 120 b proximal fromside port 118. In some embodiments, an ECG detected by electrodes 120 aand 120 b may be used to detect when catheter 110 is located withincoronary sinus 114 proximate to coronary vein 116. For example, thepresence of a relative large atrial depolarization wave, or P-wave, anda relatively small R-wave may indicate that catheter 110 is withincoronary sinus 114 rather than RV 6. The physician may identify theopening into vein 116 and advance lead 112 into the vein by feel,utilizing fluoroscopy or other visualization techniques, or any othertechnique known in the art.

Additionally, the configuration of electrodes 120 a and 120 b may enablethe detection of the location of coronary vein 116. For example, avoltage or current may be applied between first electrode 120 a andsecond electrode 120 b as the catheter is advanced through firstcoronary vein 114, and the impedance of vein wall 122 may be detected.When first electrode 120 a is advanced adjacent the orifice 124 ofsecond coronary vein 116, the detected impedance will change, indicatingthat an electrode is adjacent an orifice. In some embodiments, thedelivery catheter 110 may be advanced further, until the impedancereturns to a value indicating both electrodes are adjacent a vein wall122. The lead 112 may them be advanced through a delivery lumen (notshown) in catheter 110, out side port 118, and into second coronary vein116.

In another embodiment, a delivery catheter may be used to insert anepicardial lead through a minimally invasive substernal incision. Forexample, an incision may be made in the pericardium and the catheter maybe advanced through the incision. In some embodiments, the catheter maybe advanced over a guide wire and/or through a sheath that is positionedwithin and maintains an opening at the pericardial incision.

The delivery catheter may again include a first electrode, a secondelectrode, and a side port. The electrodes may be used to detect theECG. The amplitude of the ECG may be used to distinguish epicardial andmyocardial tissue unsuitable for pacing, e.g., ischemic or otherwisedamaged or defective tissue, from epicardial and myocardial tissue whichis suitable for pacing. In particular, the amplitude of the ECG will bediscernibly lower when the electrodes are over or contacting unsuitableepicardial and myocardial tissue.

The electrodes may additionally or alternatively be used to detectimpedance of the epicardial tissue with which the electrodes are incontact, which may additionally or alternatively be used to distinguishunsuitable, e.g., ischemic, epicardial and myocardial tissue unsuitablefor pacing from living epicardial and myocardial tissue which issuitable for pacing. In particular, unsuitable tissue may have a higherimpedance than viable tissue.

In either case, once a desired location for pacing is determined, a leadmay be advanced through a delivery lumen defined in the catheter bodyand out of the side port. The lead may be attached to the epicardialtissue and the catheter withdrawn from the delivery site through thepericardial incision.

In some embodiments, the delivery catheter may include a pre-formedcurvature similar to the natural curvature of the epicardium.Additionally, in some embodiments, the side port may be defined in aperimeter surface of the catheter which is disposed toward theepicardium when the catheter is allowed to relax towards its pre-formedcurvature.

Further, delivery catheters described herein may find applicationdelivering leads to other locations within a patient. For example, thedelivery catheters described herein may be used to deliver leads forneurostimulation therapy (e.g., spinal cord stimulation), deep brainstimulation, stimulation of one or more muscles, muscle groups ororgans, and, generally, stimulation of tissue of a patient. In otherapplications, the delivery catheters described herein can be used todeliver leads which provide muscular stimulation therapy, gastric systemstimulation, nerve stimulation, lower colon stimulation, recording ormonitoring, gene therapy, or the like.

Additionally, in some embodiments the delivery catheters describedherein can be used to deliver catheters for dispensing a drug or otherbeneficial agent from an implanted or external drug delivery device. Inshort, the delivery catheters described herein can find usefulapplication in delivery of a wide variety of leads or catheters fordelivery of therapy to a patient or for patient sensing. The patient maybe a human patient. In some cases, however, the delivery cathetersdescribed herein may be applied deliver leads or catheters to non-humanpatients.

FIG. 8 is a flow diagram that illustrates an example method ofintroducing a lead into a patient using a delivery catheter of thepresent disclosure, which, while any of the described catheters may beused, will be described with reference to the delivery catheter 8 andlead 25 of FIGS. 1 and 2.

First, the delivery catheter 8 is advanced proximate a desired location(130). In some embodiments, the delivery catheter 8 may be advancedtransvenously through a SVC 12, into a right atrium 10, through atricuspid valve 13 and into RV 6. In other embodiments, the deliverycatheter 8 may be inserted into a torso through an incision and advancedthrough an incision in a pericardium to a location adjacent epicardialtissue. In yet other embodiments, the delivery catheter 8 may beadvanced transvenously into a coronary vein. In some embodiments, thedesired location may include a His bundle 3. In other embodiments, thedesired location may include another coronary vein, an epicardial tissuewhich is not damaged or defective, or an endocardial tissue which is notdamaged or defective.

Once the catheter 8 is proximate the desired location, electrodes 27 areused to determine the desired location (132). The desired location maybe determined by detecting characteristics of a physiological waveform,e.g., a His spike within an ECG, or an impedance of tissue 29 adjacentelectrodes 27.

After the desired location is determined, a lead 25 may be advancedwithin a delivery lumen (e.g., internal lumen 22), out of side port 9and to the desired location (134). The lead 25 may then optionally beattached to the desired location, when the desired location comprisestissue 29, or the lead 25 may be advanced further, when the desiredlocation comprises a second lumen.

Finally, the delivery catheter 8 is withdrawn from the patient (136). Asdescribed briefly above, in some embodiments the delivery catheter 8 maycomprise a feature 24 oriented substantially longitudinally alongperimeter surface 17 which enables delivery catheter 8 to be easilyremoved over lead 25 by, for example, tearing the catheter. In otherembodiments, the catheter 8 may simply be withdrawn over a proximal endof lead 25.

FIG. 9 is a flow diagram that illustrates another example method ofdelivering a lead to a desired location in a patient using a deliverycatheter. The method of FIG. 9 will be described with reference todelivery catheter 90 of FIGS. 5 and 6. Similar to the embodimentillustrated in FIG. 8, the delivery catheter 90, which includes a guidewire 102 disposed in delivery lumen 92, is advanced over the guide wireuntil it is proximate to a desired location (140). Guide wire 102 mayhave been previously advanced to the desired location, prior toadvancing catheter 90 over the guide wire. Again, the desired locationmay be a His bundle, a coronary vein, an epicardial tissue which is notdamaged or defective, or an endocardial tissue which is not damaged ordefective.

The desired location is then determined using a first electrode and asecond electrode (142). In the embodiment illustrated in FIG. 9, theguide wire 102 is then withdrawn (144) from delivery lumen 92. As theguide wire 102 is withdrawn, the movable flap 100 moves from an openposition, shown in FIG. 5, to a closed position, shown in FIG. 6. Thisprovides a deflection surface which can deflect a lead 104 out of sideport 96.

A lead 104 is then advanced through delivery lumen 92 from a proximalend of delivery catheter 90. As the lead 104 is advanced and reachesmovable flap 100, movable flap 100 deflects lead 104 out of side port 96and to the desired location (146). The lead 104 may then optionally beattached to the desired location, when the desired location comprisestissue, or the lead 104 may be advanced further, when the desiredlocation comprises a second lumen.

Finally, the delivery catheter 90 is withdrawn from the patient (148).As described briefly above, in some embodiments the delivery catheter 90may comprise a feature (e.g., feature 24) oriented substantiallylongitudinally along a perimeter surface of catheter 90 which enablesdelivery catheter 90 to be easily removed over lead 104. In otherembodiments, the catheter 90 may simply be withdrawn over a proximal endof lead 104.

Various embodiments have been described. However, one of ordinary skillin the art will appreciate that various modifications may be made to thedescribed embodiments. For example, although described above withreference to embodiments in which a delivery catheter includes twoelectrodes proximate to the side port, the disclosure is not so limited.For example, delivery catheter embodiments according to the disclosuremay include three or more electrodes, or may include a single electrodeused with a remote and/or indifferent electrode for any of the detectionpurposes described herein.

Additionally, although described primarily with reference to embodimentsin which a cardiac pacing/sensing or other electrical implantablemedical lead is delivered using a delivery catheter, the disclosure isnot so limited. Delivery catheters according to the present disclosuremay be used to deliver other catheters used for delivery of drugs oragents, sensing, shunting, or any other medical purpose. Deliverycatheters according to the present disclosure may additionally oralternatively be used to deliver microstimulators, sensors, or any othersensing and/or therapeutic device or element that is implantable withina patient. Such medical devices or elements may have any configurationknown in the art. For example, implantable medical leads may have anynumber or type of electrodes coupled to one or more proximal connectorsby one or more conductors within a flexible lead body. These and otherembodiments are within the scope of the following claims.

1. A delivery catheter comprising: a catheter body comprising a proximalend, a distal end and a perimeter surface, wherein the catheter bodydefines a delivery lumen extending longitudinally within the catheterbody; a side port defined in the perimeter surface proximate the distalend and in communication with the delivery lumen; a first electrode; anda second electrode, wherein each of the first and second electrodes isadjacent to and spaced from the side port.
 2. The delivery catheter ofclaim 1, wherein the first and second electrodes are both distal fromthe side port.
 3. The delivery catheter of claim 1, wherein the firstand second electrodes are both proximal from the side port.
 4. Thedelivery catheter of claim 1, wherein the first electrode is distal fromthe side port and the second electrode is proximal from the side port.5. The delivery catheter of claim 1, wherein each of the first andsecond electrodes are each spaced at least 2 mm from the side port. 6.The delivery catheter of claim 1, wherein the catheter body furtherdefines a guide wire lumen.
 7. The delivery catheter of claim 1, whereinthe catheter body further comprises a deflection member extending intothe delivery lumen at a distal end of the side port, and wherein thedeflection member is configured to deflect an implantable element for atleast one of therapy delivery or sensing that is delivered through thedelivery lumen out of the side port.
 8. The delivery catheter of claim7, wherein the deflection member terminates the delivery lumen.
 9. Thedelivery catheter of claim 7, wherein the deflection member comprises aflap moveable between an open position and a closed position.
 10. Thedelivery catheter of claim 9, wherein the flap is configured to be movedinto the open position by a guide wire traversing the delivery lumen,move back into the closed position when the guide wire is removed fromthe delivery lumen, and deflect the implantable element that isdelivered through the delivery lumen out of the side port when in theclosed position.
 11. The delivery catheter of claim 1, wherein thedistal end comprises a blind end.
 12. The delivery catheter of claim 1,further comprising a connector at or near the proximal end toelectrically couple the electrodes to an external device.
 13. Thedelivery catheter of claim 1, wherein the delivery catheter is at leastone of steerable or preformed with a curve proximate to the distal end.14. A kit comprising: a delivery catheter comprising: a catheter bodycomprising a proximal end, a distal end and a perimeter surface, whereinthe catheter body defines a delivery lumen extending longitudinallywithin the catheter body; a side port defined in the perimeter surfaceproximate the distal end and in communication with the delivery lumen; afirst electrode; and a second electrode, wherein each of the first andsecond electrodes is adjacent to and spaced from the side port; and animplantable element for at least one of therapy delivery or sensing thatis sized for delivery through the delivery lumen and out of the sideport.
 15. The kit of claim 14, wherein the implantable element comprisesa medical lead.
 16. The kit of claim 14, wherein the implantable elementcomprises another catheter.
 17. The kit of claim 14, wherein thecatheter body of the delivery catheter further comprises a deflectionmember extending into the delivery lumen at a distal end of the sideport, and wherein the deflection member of the delivery catheter isconfigured to deflect the implantable element that is delivered throughthe delivery lumen out of the side port.
 18. The kit of claim 17,wherein the deflection member of the delivery catheter terminates thedelivery lumen.
 19. The kit of claim 17, wherein the deflection memberof the delivery catheter comprises a flap moveable between an openposition and a closed position.
 20. The kit of claim 19, wherein theflap of the delivery catheter is configured to be moved into the openposition by a guide wire traversing the delivery lumen, move back intothe closed position when the guide wire is removed from the deliverylumen, and deflect the implantable element that is delivered through thedelivery lumen out of the side port when in the closed position.
 21. Thekit of claim 14, wherein the distal end of the delivery cathetercomprises a blind end.
 22. A method comprising: advancing a deliverycatheter toward a desired location within a patient, wherein thedelivery catheter comprises: a catheter body comprising a proximal end,a distal end and a perimeter surface, wherein the catheter body definesa delivery lumen extending longitudinally within the catheter body, aside port defined in the perimeter surface proximate the distal end andin communication with the delivery lumen, a first electrode, and asecond electrode, wherein each of the first and second electrodes isadjacent to and spaced from the side port; identifying the desiredlocation with the first electrode and the second electrode; advancing animplantable element for at least one of therapy delivery or sensingthrough the delivery lumen and out the side port to the desiredlocation; and withdrawing the delivery catheter from patient.
 23. Themethod of claim 22, further comprising attaching the implantable elementto the desired location.
 24. The method of claim 22, wherein the desiredlocation comprises at least one of a living tissue, an epicardialtissue, an orifice, a patient lumen, or a coronary vein.
 25. The methodof claim 22, wherein the desired location comprises a His bundle. 26.The method of claim 25, wherein the implantable element comprises animplantable medical lead for at least one of stimulation or sensing. 27.The method of claim 22, wherein advancing a delivery catheter comprisesadvancing the delivery catheter over a guide wire disposed within thecatheter lumen, and wherein the method further comprises removing theguide wire from the catheter lumen prior to advancing the implantableelement through the catheter lumen and out the side port to the desiredlocation.
 28. The method of claim 27, wherein the delivery cathetercomprises a deflection member comprising a movable flap, wherein themovable flap is in an open position when the guide wire is disposedwithin the catheter lumen, wherein removing the guide wire from thecatheter lumen moves the movable flap to a closed position, and whereinadvancing an implantable element comprises advancing the implantableelement through the catheter lumen, and deflecting the implantableelement off the moveable flap in the closed position and out the sideport to the desired location.
 29. The method of claim 22, whereinadvancing an implantable element comprises advancing the implantableelement through the catheter lumen, deflecting the implantable elementoff a deflection member and out the side port to the desired location.30. The method of claim 22, wherein identifying a desired locationcomprises detecting an electrocardiogram via the first and secondelectrodes, and identifying the desired location based on theelectrocardiogram.
 31. The method of claim 30, wherein identifying adesired location comprises detecting a signature waveform of a Hisbundle via the first and second electrodes.
 32. The method of claim 22,wherein the implantable element comprises an implantable medical lead.